cardIncrement specifies a number of registers by which to increment when multiple dynagraph cards are available. The number of cards supported for each card type is defined by protocol.

Value:

• Must be a positive whole number.

cardRep specifies the type of DynaCard data represented by a card or block element.

Value:

• Must be defined at the card or block level for every block included in a card element.
• downhole: Indicates that the data source is downhole. If set to downhole, downholePtCount must also be defined in the parent or grandparent element.
• none: Indicates that the data source is neither downhole nor surface.
• surface: Indicates that the data source is surface. If set to surface, surfacePtCount must also be defined in the parent or grandparent element.

funcCode specifies the Modbus function code for accessing a register or block of registers.

Value:

• Must be a positive whole number.
• Must be a valid and supported Modbus function code.

See Function Codes.

len specifies the number of bytes in a data group element or register.

Value:

• Must be a positive whole number.

newTx specifies that a new message transaction starts at the block element in which newTx is defined and includes block data for all subsequent blocks until another definition of newTx set to true is encountered.

Value:

• Must be a Boolean value true or false.

ordIncrement specifies how many registers make up an increment of registers. It is always used in combination with regNum, which specifies a starting register number from which to increment.

These two attributes are used to specify one or more groups of registers that correspond to data group ordinals. ordIncrement always depends on regNum, but regNum does not depend on ordIncrement. Optionally, use regNum_ordn in place of ordIncrement + regNum.

Value:

• Must be an integer.

regBitLen specifies the length in bits of each register returned from the device for the specified funcCode. This setting can change from section to section and from register to register in the device. Refer to field device documentation for these settings.

Value:

• Must be a positive whole number.

Modbus coil data groups using function code 1, 2, 5, or 15 must use regBitLen, not regByteLen.

See also regByteLen.

regByteLen specifies the length in bytes of each register returned from the device for the specified funcCode. This setting can change from section to section and from register to register in the device. Refer to field device documentation for these settings.

Value:

• Must be a positive whole number.

Modbus coil data groups using function code 1, 2, 5, or 15 must use regBitLen, not regByteLen.

See also regBitLen.

regCnt specifies the number of registers to be returned in a block. CygNet blocks are not restricted by the Modbus maximum message size of 250 data bytes; you can specify any number of contiguous registers to retrieve per block when using the regCnt attribute.

Value:

• Must be a positive whole number.

regNum defines a starting register number.

To make this attribute meter specific, append _ordn to the attribute. For example, regNum_ord1.

To define a logical register number, as with Modbus devices, use regNum in conjunction with regOff.

To make this attribute request-type specific for use in DynaCard preCard and/or postCard elements, append _singleCard or _multipleCard to the attribute. For instance, regNum_singleCard. regNum without the appendix cannot be used in the same element as regNum_singleCard or regNum_multipleCard. If you use _singleCard or _multipleCard, you must also use the other in the same block element.

Value:

• Must be a positive whole number.

regOff defines a register offset that translates a logical register number into a physical register number. It is always used in conjunction with regNum. It may be defined in the same element as regNum, or it may be defined in a parent element then inherited by one or more regNum attributes.

regOff enables you to translate Modbus coil/register numbers into data addresses used by field devices. Modbus coil/register numbers are not the same thing as data addresses. For example, the Modbus register number 30001 typically uses the data address 0, which means that you would want to offset a regNum value of 30001 by -30001 in order to return a data address of 0 (or 0x0000).

Typical offset constants are as follows:

• -1
• -10000, -10001
• -30000, -30001
• -40000, -40001

You must consider the Modbus coil/register range convention you follow and the data addressing convention you follow. In both cases, know the range starting number and the extent of the range. The offset can be determined from the field device manual or register map.

Value:

• Must be an integer.

toDevice specifies that a block element first writes a value to a field device before the rest of a read message is executed. Used when a specification must be sent before the field device "knows" what to load and return.

Value:

• Must be a Boolean value true or false.

txMaxRegCnt specifies the maximum number of registers that may be communicated in a single transaction. This attribute is optional and intended to provide a way to make messages for a single block smaller than the Modbus maximum message size of 250 data bytes. How many registers you read or write within byte constraints depends on the size of the registers with which you are communicating.

txMaxRegCnt is used in conjunction with the regCnt attribute. regCnt specifies the number of registers to be returned in a single block; txMaxRegCnt merely constrains the size of the message(s) used to communicate registers. For example, if you want to retrieve 125 2-byte registers in a single message, set regCnt to 125 and do not use txMaxRegCnt. But if you want to retrieve 125 2-byte registers in five messages, set regCnt to 125 and txMaxRegCnt to 25.

Value:

• Must be a positive whole number.
• Cannot exceed the number of registers that the Modbus maximum message size of 250 data bytes can accommodate.

type defines the appropriate data type for one or more DataGroupElement elements; it can be inherited from a parent element.

Value:

• bin.hex: Binary hex
• boolean: Boolean
• i1: Character
• i2: Short integer
• i4: Integer
• i8: Integer
  
• r4: Float
• r8: Double
• ui1: Byte
• ui2: Unsigned short integer
• ui4: Unsigned integer
• ui8: Unsigned integer
• string: String
• struct: Structure

See also sourceType.

Reads contiguous coil statuses from 1 - 2000. Registers must be read-only Boolean.

Reads contiguous discrete input statuses from 1 - 2000. Registers must be read/write Boolean.

Reads contiguous contents of a block of holding registers. Registers must be read-only 16 or 32 bit.

Reads contiguous input registers from 1 - 125. Registers must be read/write 16 or 32 bit.

Writes ON or OFF to a single coil. Registers must be read/write Boolean.

Writes data to a single holding register. Register must be 16 or 32 bit.

Reads the contents of eight exception status outputs in a remote device.

Writes ON or OFF to multiple coils in sequence. Registers must be Boolean.

Writes data to a block of contiguous registers from 1 - 123. Registers must be 16 or 32 bit.